Oxygen consumption by the coastal bottom sediments (North Caucasian sectorof the Black Sea)

Box experiments performed in Rybatskaya Bight of the Black Sea (five miles to the north of Gelendzhik) allowed us to determine the values of oxygen co nsumption in the bottom sediments. Along with the oxygen flux values common ly observed in the box experiments in the shelf zone (in our case, 26.8 mM m(-2) day(-1)), significantly higher values of the fluxes (60.2 MM m(-2) da y(-1)) were obtained for the bottom sediments that contain hydrogen sulfide immediately from their surface. The hydrogen sulfide released is oxidized by the oxygen of the near-bottom water. The flux values cited, obtained for the closed systems of boxes, being reduced to the open system of the seafl oor by introducing experimentally determined reductions (hydroquinone), pro duce the values 123.7 and 1005 mM m(-2) day(-1), respectively. The latter v alue is a peak and exceeds all the estimates known from publications. The g reat difference in the fluxes suggests a mosaiclike structure of the sedime nts studied that is irregular with respect to the sedimentation conditions and organic matter contents. The role of benthos and rate of hydrogen sulfi de oxidation are estimated.